Vulcanization of rubber



Patented Oct. 10, 1939 UNITED STATES PATENT OFFICE VULOANIZATION F RUBBER Albert M. Clifford, Stow, Ohio, assignor to Wingfoot Corporation, Wilmington, Del., 2. corporation of Delaware No Drawing. Application November 7, 1935,

Serial No. 48,692

Claims. (Cl. 18-53) This invention relates to a new class of chemi- Other thiazoles may be substituted for the mercal compounds suitable for use as accelerators of captobenzothiazole of the example. These others the vulcanization of rubber. It includes the cominclude l-mercapto thiazole, l-mercapto l-phenyl pounds themselves, a method of preparing them, thiazole, the 1-mercaptonaphthothiazoles, l-mertheir use in rubber, and the rubber product decapto 3 methyl benzothiazole, l mercapto rived thereby. 5-ethoxy benzothiazole, l-mercapto 5-nitro ben- A number of compounds are known which are zothiazole, l-mercapto 5-hydr0xy benzothiazole, reaction products of mercaptazoles and imids. l-mercapto 5-ch1oro benzothiazole, l-mercapto Representative are those disclosed in United 5-phenyl amino benzothiazole, the l-mercapto States Reissue Patent 19,286. However, none of xylyl thiazoles, 1-mercapto 5-nitro 4-chloro ben- 1 th disclosed compounds i p y h g ping zothiazole and other l-mercapto ring substituted 0 the Compounds of the present ven arylene thiazoles. Also, the invention is not These compounds are derived from mercaptalimited to their sodium salts. Other reactive 01 5 d diimidsy a e fOrmula salts, as potassium, calcium, etc. may also be 1 used.

5 Also, the p-benzoquinone-dichloro 'imid maybe 3 replaced by the orthocompound or the analogous Also, compounds of the phenazine type may be employed. Also, the other halogens, such as in which R and R3 are mercaptazole residues and R1 and R2 are aryl nuclei or are combined to form one aryl nucleus. bromine may be substituted for chlorine.

Representative of these compounds is bis thio The structural formulae of some representabenzothiazyl p-quinone diimine. This material tive compounds of the invention obtained by may be prepared as follows: A mixture of 26.3 employing the foregoing reactants follow: X 06 C-S-N =NSC Q grams of p-benzoquinone dichloro imid and 63 (3H3 grams of sodium benzothiazyl mercaptide in 350 cc. of dry benzene was refluxed on a water bath for about two and a quarter hours. The reaction C1360 OCHHH mixture was cooled, filtered, and dried. The soluble sodium salts formed were removed by triturating in water. The residual solid was filtered N\ off, washed, and dried. The product, weighing 60.2 grams, was a dark red-maroon solid, which C1 C] melted at 208210 C. after recrystallization from xylene. Analysis showed it to contain 11.97% 40 nitrogen and 29.3% sulphur, compared with the calculated values for bis thio benzothiazyl p-quinone diimine of 12.83% and 29.40%, respectively. (31 s It has been found that best results are ob- SC\ tained when the reaction is conducted under sub- 5 C1 stantially anhydrous conditions. The reactant materials are dried if necessary and a dry nonreactive medium such as toluene, xylene, or other aromatic hydrocarbons is preferably used.

The reaction may be represented by the following equation:

naphthoquinoneand anthraquinone compounds.

It will, of course, be understood that the forey going compounds are merely representative and are in no way to be construed as limitative of the invention. It is intended that the compounds include broadly the derivatives of any mercaptazole and any di imido aryl substance as typified by the quinone and phenazine type compounds.

The compounds of the invention may be employed as accelerators in most of the ordinary rubber mixes. The following is one specific formula in which they have been found by trial when his thio benzothiazyl p-quinone diimine was employed as the accelerator were as follows:

Ul't t NiOdI/IIUS Tensile me e gs. cm. Cure 111 minutes at F. elongakgs/cm tion Percent No cure 1 950 7 16 830 18 60 770 26 102 Examination of the data readily shows the very desirable curing characteristics obtained, particularly the absence of cure in the early stages.

This will permit use of the compounds in mixes subjected to very severe processing conditions previous to vulcanization.

The compounds may also be used in conjunction with basic nitrogen-containing accelerators such as the diaryl guanidines, the aldehydeamine accelerators, butyl ammonium oleate, di-

phenyl guanidine phthalate, dibenzyl amine, etc.

While only the preferred forms of the invention have been described in detail, it will be apparent to those skilled in the art that many variations may be made therein without departing from the spirit of the invention or the scope of the appended claims in which it is intended to claim all features of patentable novelty residing in the invention.

What I claim is:

1. The method of treating rubber which comprises vulcanizing it in the presence of an N, N bis (l-thio thiazyl) quinone di imine.

2. The method of treating rubber which comprises vulcanizing it in the presence of an N, N bis (l-thio thiazyl) benzoquinone di imine.

3. The method of treating rubber which comprises vulcanizing it in the presence of an N, N bis (l-thio thiazyl) naphthoquinone di imine.

4. The method of treating rubber which comprises vulcanizing it in the presence of an N, N bis (l-thio benzothiazyl) benzoquinone di imine.

5. As new compounds, the N, N bis (1-thio thiazyl) quinone di imines.

6. As new compounds, the N, N bis (l-thio benzothiazyl) benzoquinone di imines.

7. A rubber product which has been vulcanized in the presence of an N, N bis (l-thio thiazyl) quinone di imine.

8. As new compounds, the N, N thiazyl) benzoquinone di imines.

9. As new compounds, the N, N thiazyl) naphthoquinone di imines.

10. As a new compound, N, N benzothiazyl) p-quinone di imine.

11. The method of treating rubber which comprises vulcanizing it in the presence of N, N bis (l-thio benzothiazyl) p-quinone di imine.

12. A rubber product which has been vulcanized in the presence of an N, N bis (l-thio bis (l-thio bis (l-thio bis (l-thio thiazyl) benzoquinone di imine.

13. A rubber product which has been vulcanized in the presence of N, N bis (l-thio thiazyl) 14. A 

